Outer Joins

Hello,

i am trying to convert the code in oracle to postgres. i am new to postgres however, am aware that + sign is not supported unlike oracle. So could i get help in rewriting the below query in oracle into postgres please:

SELECT t1.col1 , t2.col2, t3.col3, t4.col4
FROM t1, t2, t3, t4
WHERE t4.x1 = t1.a1(+)
AND t4.x2 = t2.x2
AND t4.x3 = t2.x3
AND t4.x4 = t2.x4
AND t4.x5 = t2.x5

Thanks